Safety-switch.



H. B. SHRBVE.

SAFETY SWITCH. APPLICATION FILED MAY 26,1910.

1,039,600, Patented Sept. 24, 1912.

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UNITED STATES PATENT OFFICE.

HARRY B. SHBEVE, OF CHICAGO, ILLINOIS, ASSIGNOB, BY DIRECT AND MESNE .ASSIGIL- .MENTS, -T0 LEWIS B. JENKS, OF GHICAGO,..ILIJINQIS.

SAFETY-SWITCH.

specification of Letters Patent. I Patented Sept, 24, 1912.

. Applicationflled Kay 26, 1910. Serial 110.483.598. j

To all whom it mag concern;

Be it known that I, HARRY B. 'Srrrmvn, a citizen of the United States, residing at Chicago, in the county of Cook and State-of Illinois, have invented certain new and useful Im rovements in Safety-Switches, of which t e following is a specification.

This invention relatesto a form ofsafety the switch casing, the circuit being closed as long as said finger is depressed and being opened automatically when the finger is allowed to move out.

As before stated, the switch is intended, particularly for use in elevator systems where it is desired to interlock the opening and closing of the several gates with the brake mechanism of the elevator, but it will be ap arent that the swit'ch is in no wise limite to such use.

The main objects of the invention are, to provide a switch of extremely simple desi and construction; one which is normally open and will only remain closed while pressure is applied to the actuating finger; one which is completely inclosed within a fireproof casing, and one which is of such design and construction that it'may be insulated in a most efiicient' manner with the least amount of insulating material.

Other objects and uses of the invention will appear from a detailed description of the same, which consists in the features 0t construction and combination of parts here inafter described and claimed.

Referring now to the drawing,-Figure 1 shows a plan view of the switch, the cover being removed'and thefinger being in extended position so that the circuit is broken; Fig. 2 IS a view similar to that of Fig. 1,

' the finger being depressed, however, to close.

the circuit; and Fig. 3 is a cross-section taken on the line 3-3 of Fig. 1 looking in the direction of the arrows.

Referring now to the drawing, the switch mechanism is inclosed within a housing 24, havin side walls 25 and 26 and end walls 3 28. A cover 44, which is'provided around its periphery with a heading as illustrated in Fig. 3, may be held in position against the slde and end wallsby means of a screw 45 threaded into a' boss The bottom of the 'interior of the box is, properly lined with insulating material 48 and a block 36 of insulating material is suitably attached to the bottom of the interior at approximately its central portion.- The electrical contacts 37 and.38 are secured' to the insulating block 36 and have. their contact faces bent down over the edge of the insulating block. The electrical leads 39 and 40 are connected to the contacts'37 and 38, respectively, and pass out :otgthe box through a threadedneck 41, which is adapted to receive the end of an electric conduit e. Finger 29 is slidably mountedwithin the box and has its direction of movement de- .termined by its end portion 31, which passes through the rear wall of the box, and by its contact head 30, which extends through the forward end of the box. A lug 43 is secured to the bottom of the box and limits .the amount of, outward movement of the finger by contacting with a collar 32 on the, finger. A spring 33, surrounding the end portion 31, contacts the interior ofthe rear wall of the box and the collar and tends to maintain the finger in projected osition as shown in Fig. 1. It is preferre that a partition 42' block 34 is mounted on the gage the down-turned faces of the contacts 37 and 38 when the finger is pushed backinto the position shown in Fig. 2. It is thus seen that when the finger is forced inward the circuit between the'contacts 37 and 38 is closed, while when the finger is released it will be, projected into the position shown inFig. 1 to break the circuit.

It is cover 5 ould be? providedywith insulating material 49. Byreason of the relative-arrangements of the contacts withrespect to the other portions of the .switch,:anyiflash ing which may occur; when the switch is opened fwill befconfined to the extremeinterior-port-ion of the switch, the only met'allie portions thereof to which. thefiash might referred that the .inner face of the we jump being the bottom of the box and the coven. However, inasmuch as these parts are thoroughly insulated by, the layers of insulation 48 and 49, it is seen that it is practically impossible for the Hash to extend to any portion of the box, and thus danger from short circuits and burn-outs is largely eliminated.

In practice the switch would ordinarily be placed with its finger extending in a horizontal position. Therefore, any moisture which might tend to enter the box and thus reduce the electrical insulation would be caught within the partition 42 and there held, thus again greatly increasing the etticiency of the insulation.

1 claim:

In a self-opening safety switch the combination of a base member, a surrounding wall on the same, insulating material on that portion, of the base includer Within such Wall, a stationary insulating block within the inclosing wall, a pair of stationary contacts secured to said block and each provided with a down-turned contact finger lying on the edge of the insulating block, a plunger ing the circuit, a spring on the plunger arm for projecting the same in one direction to thereby move its insulating block and spring contacts sidewise for opening the circuit, a cover plate adapted to be held in position against the upper edge of the inclosin wall, and insulating material on the inner face of said cover plate, substantially as described.

HARRY B. SHREVE.

Witnesses:

WM. P. Bonn, MARY R. Fnosr. 

